Understanding the molecular mechanisms governing temporal control of developmental processes is the main focus of this research. Cells need to "know" when to proliferate versus when to terminally differentiate. Failure to achieve this strict developmental timing control could lead to detrimental effects such as the formation of cancerous cells. Caenorhabditis elegans is an excellent model organism for studies of developmental timing. Mutations that alter the normal timing of hypodermal terminal differentiation have been identified. lin-57 is one of these genes. The role of lin-57 in restricting hypodermal terminal differentiation to the final molt will be investigated. Genetic and molecular approaches will be used to cloned lin-57 and the molecular nature of the product it encodes will be studied in detail. Temporal and spatial patterns of lin-57 gene expression will be assayed with reporter fusions, northern blots and immunolocalization techniques. In addition, partial characterization of putative novel genes involved in the timing of hypodermal terminal differentiation will be performed. Elucidation of this information will contribute to a better understanding of the molecular basis of biological timing mechanisms.